Technical Field
The present disclosure relates to a sealing structure with a torsional damper and an oil seal, and particularly relates to a sealing structure comprising a torsional damper to absorb a torsional vibration generated from a rotary shaft of an engine of a vehicle or the like, and an oil seal for the torsional damper.
Background Art
In an engine of a vehicle, for example, a torsional damper is attached to one end of a crankshaft to reduce a torsional vibration caused by a rotational fluctuation of the crankshaft. The torsional damper used in the engine of the vehicle is typically in the form of a damper pulley and transmits part of the power of the engine to auxiliary machinery, such as a water pump, a compressor of an air conditioner or the like, through a power transmission belt. The gap between the torsional damper and, for example, a through-hole of a front cover into which the crankshaft is inserted is sealed by an oil seal.
FIG. 22 is a partial cross-sectional view taken along an axis, schematically showing a conventional arrangement of a damper pulley and an oil seal of an engine of a vehicle. As shown in FIG. 22, a conventional damper pulley 100 includes a hub 101, a pulley 102, and a damper elastic body 103 disposed between the hub 101 and the pulley 102. The hub 101 includes a boss part 101a on the inner periphery side, a rim part 101b on the outer periphery side, and a disk part 101c connecting the boss part 101a and the rim part 101b to each other. The damper pulley 100 is fixed to a crankshaft 120 by a bolt 121 with the boss part 101a of the hub 101 fitted into one end part of the crankshaft 120.
The boss part 101a of the hub 101 of the damper pulley 100 attached to the crankshaft 120 is inserted into a through-hole 123 of a front cover 122 from outside of the engine, an oil seal 110 is press-fitted into the gap between the boss part 101a and the through-hole 123, and a seal lip 111 slidably abuts in a fluid-tight manner against the boss part 101a to form a seal between the damper pulley 100 and the front cover 122.
With such a conventional arrangement of the damper pulley 100 and the oil seal 110, foreign matter can enter between the oil seal 110 and the boss part 101a, and if the seal lip 111 catches the foreign matter, the seal lip 111 may be damaged or deteriorated, and the sealing performance of the oil seal 110 may deteriorate, leading to oil leakage. To avoid this, there is disclosed a structure that reduces entry of foreign matter between the oil seal 110 and the boss part 101a through the gap between the damper pulley 100 and the front cover 122 (for example, see Japanese Patent Application Publication No. 09-324861).
In addition, to reduce the weight and manufacturing cost, some conventional damper pulleys 100 have a plurality of windows 101d as through holes passing through the disk part 101c of the hub 101, circumferentially formed (for example, see Japanese Utility Model Application Publication No. 05-25049 and Japanese Patent No. 5556355).
However, the conventional damper pulley 100 with the windows 101d is susceptible to entry of foreign matter such as muddy water, sand or dust to the side of the engine through the windows 101d, although the damper pulley 100 has a reduced weight and is manufactured at reduced cost in the engine. Thus, such a torsional damper with windows requires further improvement in the capability of reducing entry of foreign matter to the seal part.
As described above, when the conventional damper pulley 100 with the windows 101d is used, there is a demand for further reducing exposure of the seal lip 111 of the oil seal 110 not only to foreign matter entering from around the outer periphery of the damper pulley 100 but also to foreign matter entering through the windows 101d. Furthermore, with the increasing diversity of the use environment of vehicles in recent years, there is a demand for further reducing exposure of the seal lip 111 of the oil seal 110 to foreign matter entering from the outside.
The present disclosure is related to provide a sealing structure with a torsional damper and an oil seal that can reduce exposure of a seal lip of the oil seal to foreign matter entering from around the torsional damper.